1. Field of the Invention
The invention generally relates to means for providing a warning that the temperature in a food storage freezer is approaching a level whereat the frozen goods contained within the freezer are susceptible to thawing. In particular, the invention provides a switch and alarm system for signalling the operational failure of a freezer device.
2. Description of the Prior Art
Perishable foods and pharmaceuticals inter alia have long been frozen in order to prolong the useful life of such materials. In order to prevent spoilage of frozen consumable items and to maintain the quality of such items, it is important that these items remain frozen at all times after the initial freezing and until such time as the items are prepared for serving. Pharmaceuticals and similar substances which are typically maintained in hospitals and the like are often subject to rapid decomposition unless maintained in a low-temperature environment. Since freezing equipment is subject to unexpected failure, not only due to mechanical failure, but also due to unexpected power losses which can go undetected for relatively long periods of time under certain circumstances, frozen materials or materials maintained at a low temperature can thus be subject to spoilage if the freezer malfunction goes undetected. Devices previously provided for indicating a degradation of desired temperature conditions within a freezer have generally proved unsatisfactory when only a visual indication of the relatively high temperature conditions within the freezer was provided. In U.S. Pat. No. 3,896,278, issued to Murawski, et al., a gravity actuated plunger is retained in place by a freezable liquid, the plunger being maintained in spaced relation from an electrical contact until the freezable liquid is caused to melt by virtue of undesirably high temperatures within the freezer. Melting of the freezable liquid allows gravitationally induced movement of the plunger into electrically-conductive contact with the contact member, thereby initiating an audible alarm. The Murawski device, while providing a function similar to that of the present invention, is more complex in operation and, therefore, more subject to wear and consequent failure.